Two-stage fuel unit



Dec. 22, 1964 w, so 3,162,129

TWO-STAGE FUEL UNIT Filed July 13, 1962 12 ll 13 22 J0 IN VENTOR.

Jiaberi [ZZZ 7 71165027 United States Patent 3,162,129 TWD-STAGE FUEL UNET Robert W. Eriksou, Rockford, Ill., assignor to Sundstrand Corporation, a corporation of lilinois Filed July 13, 1962, Ser. No. 269,595 Claims. (Cl. 1032) This invention relates to a pump and more particularly to a pump capable of operating satisfactorily in a number of different mounting positions.

It is the general object of the present invention to produce a new and improved pump of the character described.

It is a more specific object of the invention to produce a pump particularly adapted for use as an oil burner pump which will be operative to deliver oil at the required pressure to an oil burner nozzle and which is capable of so functioning in a variety of different mounting positions.

A further object of the present invention is to produce a two-stage oil burner pump wherein the first stage draws oil from a tank or other source of supply into a reservoir in which the inlet to the second stage pump is located, and which is so arranged as to provide substantially air-free oil to the inlet of the second stage in various mounting positions of the pump.

Other and further objects of the present invention will be readily apparent from the following description and drawings, in which:

'FIG. 1 is a longitudinal section through a two-stage oil burner pump embodying the invention;

FIG. 2 is a vertical section taken along line 22 of FIG. 1;

FIG. 3 is a view like FIG. 2 but illustrating the location of the parts with the pump rotated 180; and

FIG. 4 is a view like FIG. 2 wherein the pump has been rotated 270 in an anticlockwise direction.

While this invention is susceptible of embodiment in many difierent forms, there is shown in the drawings and will herein be described in detail one specific embodiment of the invention, with the understanding that the present disclosure is to be considered as an exemplifioation of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

The present invention has been illustrated as embodied in a two-stage oil burner pump. Two-stage units are generally designed for installations where long inlet lines or high lift conditions are involved. The first stage of the pump serves to draw oil from the source to the reservoir in which the inlet of the second stage is located. The inlet vacuum to the first stage, where high lift conditions exist, can be as high as 18 or 20 inches. Under these relatively high vacuum conditions, the existence of air leaks at inlet line joints and connections causes a mixture of both oil and air to be drawn into the reservoir by the first stage of the pump. This air should be prevented from entering the inlet of the second stage pump and thus that inlet should be located well belowthe oil level in, the reservoir so that flotation separation of air bubbles within the oil will provide for clear oil only to enter the second stage inlet. As is well known, the presence of air in the oil delivered to the oil burner nozzle causes impaired operation, particularly on shutdown where smoke may be formed, resulting in the deposition of soot on the heat exchanger surface thereby impairing the efficiency of the furnace or boiler with which the oil burner is, associated.

Under circumstances where a long inlet line or high lift is encountered, it has been the practice to utilize such two-stage pumps and examples thereof are to be found in the patents to Erikson, No. 2,751,847, and Kiefer, No..

2,657,632. The present invention may be said to be an improvement over the two-stage pump shown in the Erikson patent, reference to which may be had for further details of construction of the unit which are not pertinent to the invention disclosed herein.

Referring now to the drawings, there is shown a pump having a casing 10 closed at one end by an end cap 11 and provided with an inlet communicating with a space 12 within the casing which, in turn, opens into a chamber 13 therein. A screen 14 is provided in the chamber for screening out foreign particles in the oil and there is defined within the screen a reservoir 15.

A first stage pump 16 is provided for drawing oil from the source into the inlet 12 and hence through the screen 14 into the reservoir 15. The first stage pump is of the gear-crescent variety of the type illustrated in the Erikson patent hereinbefore referred to and includes an outer stationary ring 17 and a ring gear 18 rotating within the confines of the outer ring, with a portion of the teeth of the ring gear meshing with the teeth ofa spur gear 19. The spur gear has an outer diameter smaller than the inner diameter of the ring gear and the space which exists therebetween is closed by a crescent 20, and intake kidney 21 communicates with the inlet of the first stage pump.

A second stage pump 22 is separated from the first stage pump by a spacer plate 23 in which the kidney 21 is located. The second stage pump also includes an outer ring 24, an internflly toothed ring gear 25 meshing with a spur gear 26 and separated therefrom in the area opposite the point of mesh by a crescent 27. The second stage pump is provided with an intake port 28. A shaft 29 is rotatably mounted in the casing and carries the spur gears 19 and 26. Power applied to the shaft 29 serves as the driving power for both the first and second stage pumps, and a shaft seal 30 of the usual construction prevents oil leaking along the shaft from escaping to the exterior of the housing. Discharge from the first stage pump is into a conduit 31 communicating with the shaft seal and thence into a conduit 32 communicating with the interior portion of a burner shutoff valve 33. The interior portion of said valve is connected to the chamber 13 by passage 34. Discharge from the second stage pump is into a pressure conduit 35 connected to the burner port controlled by the valve 33 for delivery to the nozzle of the burner.

In the construction shown in said Erikson patent, the intake kidney 21 of the first stage is connected by means of a passage to the upper portion of the reservoir and discharge from the first stage pump serves to maintain the reservoir substantially filled with oil so that the intake of the second stage pump is well below the level thereof and hence is in communication with air-free oil. In such an arrangement, however, the pump must be mounted in a single predetermined position in order for the parts to function properly.

In accordance with the present invention, however,

at least two inlet channels are provided communicating with the intake kidney 21. In theembodiment illustrated, these take the form of channels 40 and 41 extending generally oppositely from the intake kidney 21 and each opening into the reservoir 15. Each of the channels is sized so as to provide for the passage of insuflicient oil to meet the suction demands at the intake kidney 21 so that, for example, in the position shown in FIG. 1, even though oil is flowing through the lower channel 41 a vacuum still exists in the upper channel 40 and thus oil is further drawn into the reservoir until the reservoir is filled and its level is at the upper inlet passage ofthe channelAil.

the same situation exists, i.e., a vacuum will still exist in the upper channel 41 in spite of the presence of the lower channel 40, and oil will continue to be drawn into the reservoir until it reaches the level of the opening of the channel 41. Thus, in the two cases illustrated in FIGS. 2 and 3, a head h will exist above the inlet 28 to the second stage. i i 7 In FIG. 4 of the drawings, the unit has been rotated approximately 270 anticlockwise from the position shown in FIG. 2. This places the inlet 28 to the second stage in the lowermost position. The openings of the channels 40 and 41, however, are still above this point and a head of oil Jr will exist in this position. It would be undesirable, of course, to mount the pump in a position 180 from that shown in FIG. 4 as this would place the inlet 28 at the top of the reservoir where non-air-free oil would be drawn into the second stage.

A two-stage pump manufactured in accordance with the present invention thus provides a unit which may be tion, a casing, a first stage pumping means in the casing,

a second stage pumping means in the casing, a reservoir in the casing to which the inlet to the second stage pumping means is connected, and a shaft rotatably mounted in the casing for driving said pumping means, means associated with said pumping means for maintaining a level of oil in the reservoir above the position of said inlet to the second stage pumping means at various rotative positions of the pump relative to said shaft, comprising, means providing at least two channels, each communicating at one end with the inlet to the first stage pumping means and opening at the other end to the reservoir at spaced apart points, said channels each having a fluid flow capacity less than the pumping capacity of said first stage pumping means whereby a'vacuum exists in each of said channels during operation of said oil burner pump.

2. The two-stage oil'burner pump of claim 1 in which said points are spaced apart by at least 90.

3. The two-stage oil burner pump of claim 1 in which said other ends of the channels open to the reservoir at substantially opposite sides thereof.

4. In a two-stage oil burner pump having in combina tion, a casing, a first stage pumping means in the casing, a second stage pumping means in the casing, a reservoir in the casing to which the inlet to the second stage pumping means is connected, and a shaft rotatably mounted in the casing for driving said pumping means,'means associated with said pumping means for maintaining a level of oil in the reservoir above the position of said inlet to the second stage pumping means at various rotative positions of the pump relative to said shaft, comprising, a spacer plate positioned between and separating the first and second stage pumping means, a pair of channels formed in said spacer plate, each communicating at one end with the inlet to the first stage pumping means and opening at the other end to the reservoir at points spaced apart by at least the oil flow capacity of each of said channels being less than the capacity of said first stage pumping means whereby a vacuum exists in each of said channels.

5. In a two-stage oil burner pump having in combination, a casing, a shaft rotatably mounted in the casing, 21 first stage gear pump in the casing having a spur gear mounted on said shaft, a second stage gear pump in the easing having a spur gear mounted on said shaft, a reservoir in the casing to which an inlet to the second stage pumping means is connected, means associated with said pumps for maintaining a level of oil in the reservoir above the position of said inlet to the second stage pumping means at various rotative positions of the pump relative to said shaft, comprising, a spacer plate surrounding said shaft and positioned between and separating said first and second stage gear pumps, a pair of oppositely extending channels formed in said spacer plate, each communicating at one end to the inlet of the first stage gear pump and opening at the other end to the reservoir substantially on opposite sides thereof, the oil flow capacity of each of said channels being less than the capacity of said first stage pumping means whereby a vacuum exists in each of said channels.

References Qited in the file of this patent UNITED STATES PATENTS 

1. IN A TWO-STAGE OIL BURNER PUMP HAVING IN CONBINATION, A CASING, A FIRST STAGE PUMPING MEANS IN THE CASING, A SECOND STAGE PUMPING MEANS IN THE CASING, A RESERVOIR IN THE CASING TO WHICH THE INLET TO THE SECOND STAGE PUMPING MEANS IS CONNECTED, AND A SHAFT ROTATABLY MOUNTED IN THE CASING FOR DRIVING SAID PUMPING MEANS, MEANS ASSOCIATED WITH SAID PUMPING MEANS FOR MAINTAINING A LEVEL OF OIL IN THE RESERVOIR ABOVE THE POSITION OF SAID INLET TO THE SECOND STAGE PUMPING MEANS AT VARIOUS ROTATIVE POSITIONS OF THE PUMP RELATIVE TO SAID SHAFT, COMPRISING, MEANS PROVIDING AT LEAST TWO CHANNELS, EACH COMMUNICATING AT ONE END WITH THE INLET TO THE FIRST STAGE PUMPING MEANS AND OPENING AT THE OTHER END TO THE RESERVOIR AT SPACED APART POINTS, SAID CHANNELS EACH HAVING A FLUID FLOW CAPACITY LESS THAN THE PUMPING CAPACITY OF SAID FIRST STAGE PUMPING MEANS WHEREBY A VACUUM EXISTS IN EACH OF SAID CHANNELS DURING OPERATION OF SAID OIL BURNER PUMP. 